Aluminum phosphate composite materials and compositions

ABSTRACT

AlP composite materials comprise an AlP aggregate core, and a shell disposed partially or entirely over the core and formed from a pigment material, e.g., TiO 2 , having an index of refraction greater than the core, providing an overall index or refraction greater than the core and suited for use as a pigment replacement or extender. The AlP core comprises amorphous AlP, crystalline AlP, or a combination thereof, and can have an average particle size of less than about 30 microns. The TiO 2  can have an average grain size less than about 10 microns. The shell can have a layer thickness that is at least about 0.0001 microns. The shell is bonded to the core by a reaction between functional groups of the shell and core. The AlP composite material can be engineered to provide properties in addition to brightness for use as a pigment such as anticorrosion and/or antimicrobial protection.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. application Ser. No.13/708,810, filed Dec. 7, 2012, now U.S. Pat. No. 9,475,942, issued Oct.25, 2016, which application is herein incorporated by reference in itsentirety.

FIELD

Aluminum phosphate composite materials and compositions comprising thesame are disclosed herein that are engineered to provide propertiesmaking them useful as a pigment replacement and/or pigment extender,e.g., for use in place of conventional pigments such as TiO₂ and thelike, and that can provide additional properties not otherwise presentwith such conventional pigments .

BACKGROUND

The use of conventional pigments such as TiO₂ and the like in coatingformulations is well known. TiO₂ pigments are the widest used pigmentsin the coatings industry, as they are used in virtually all white orpastel coating compositions because of its brightness and very highrefractive index (having an index of refraction of about 2.61). Whilesuch conventional TiO₂ pigments are useful for providing a desired levelof brightness and high refractive index in coating formulations, the rawmaterial cost of conventional TiO₂ has increased over the years,reducing the profit margin obtainable for chemical formulations orcoating products containing the same if the raw material cost increasecannot be passed onto the product consumer.

Also, while TiO₂ is useful for providing a desired degree of brightness,it alone is not useful for introducing one or more other performanceproperties that may be desired into a particular chemical or coatingformulation. Accordingly, chemical or coating formulations calling forperformance properties in addition to brightness conventionally rely onadditives or agents in addition to TiO₂, thereby adding further to thecost and/or complexity of formulating the chemical composition orcoating.

It is, therefore, desired that a composite material be developed in amanner that provides pigment performance characteristics, e.g.,brightness and high refractive index, that are the same as or similar tothat of conventional pigments such as TiO₂, e.g., to serve as a primarypigment replacement or as a pigment extender, and that is more costefficient when compared to conventional TiO₂ from either a raw materialand/or a formulated coating cost per unit volume solids. It is alsodesired that the composite material be one that is capable of providingone or more performance properties in addition to brightness to enablemaking chemical or coating formulations calling for such additionalperformance properties without having to rely on additional additives oragents.

SUMMARY

Aluminum phosphate composite materials as disclosed herein comprise acore and shell structure, wherein the shell is formed from a materialhaving an index of refraction that is higher than the core to provide anthe composite material with an overall index of refraction that isgreater than the core, and wherein the core is formed from a materialhaving a reduced material cost when compared to the shell. In anexample, the core comprises an aggregate of joined-together primaryaluminum phosphate grains or powder, and the aggregate is herebyreferred to an AlP particle. The AlP particle can comprise amorphousAlP, crystalline AlP, or a combination thereof. The AlP particle canhave an average particle size of less than about 30 microns, in therange of from about 3 to 20 microns, and preferably in the range of fromabout 5 to 10 microns. The AlP can be made by precipitation, binarycondensation, and sol gel methods of making.

In such example, the shell is provided in the form of a layer of pigmentmaterial disposed over an outside surface of the core. A preferredpigment material is TiO₂. The TiO₂ can have an average grain or powdersize that is less than about 10 microns, in the range of from about 0.1to 5 microns, and preferably in the range of from about 0.3 to 1microns. The shell has a layer thickness that is at least about 0.0001microns, and between about 0.001 to 2 microns, and preferably in therange of from about 0.01 to 1 microns. Generally, the shell layerthickness can comprise as little as a single grain, or can compriseseveral grains that are bonded or otherwise combined together on thecore surface.

The shell may cover all or only a portion of the AlP core. In anexample, the shell covers at least 20 percent of the total outsidesurface of the core, in the range of from about 30 to 100 percent of thetotal outside surface of the core, and preferably 20 percent of the coreoutside surface, and preferably in the range of from about 50 to 75 ofthe core outside surface. In an example, the TiO₂ is treated with orotherwise comprises a material that reacts with pendant POH groups fromthe AlP core to form a reaction product therebetween that operates tobond the shell to the core.

If desired, the AlP composite material can be engineered to provideproperties in addition to being a pigment and/or pigment extender. In anexample, the AlP composite can produce a controlled release of phosphateanion when placed into contact with moisture to provide a desired degreeof anticorrosion protection. Additionally, the AlP composite materialcan be engineered to produce a controlled release of one or more otherelements or compounds useful for providing anticorrosion, and/or forproviding other properties such as antimicrobial and/or antifoulingprotection.

AlP composite materials as disclosed herein can be used as the solepigment in a chemical or coating composition, e.g., comprising a bindingpolymer. In an example, the AlP can be used to replace about 100 percentof conventional pigment material. In another example, AlP compositematerials as disclosed herein can be used in conjunction withconventional pigments to offset the amount, and thereby the cost, ofsuch other conventional pigment that is used, and can comprise at leastabout 5 percent by weight of the total pigment used in a formulation, inthe range of from about 10 to 80 percent by weight of the total pigmentused, and in the range of from about 20 to 60 percent by weight of thetotal pigment used in a chemical or coating formulation. AlP compositematerials as disclosed herein present a more cost-effective option thanconventional pigment materials such as TiO₂ from either a raw materialand/or a formulated coating cost per unit volume solids. Additionally,such AlP composite material are capable of being engineered to introduceone or more other performance property, in addition to brightness, toenable making chemical or coating formulations calling for suchadditional performance properties without having to rely on additionaladditives or agents.

DESCRIPTION OF THE DRAWING

These and other features and advantages of aluminum phosphate compositematerials and compositions and methods for making the same as disclosedherein will be appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with FIG. 1, which is a photomicrograph showing across-sectional view of an example aluminum phosphate composite materialas disclosed herein.

DETAILED DESCRIPTION

Aluminum phosphate composite materials and compositions comprising thesame as disclosed herein generally comprise a two-component structuremade up of a centrally oriented core, and a shell disposed around orover all or part of the core. In an example, the core is formed from anon-TiO₂ material such as aluminum phosphate that provides a costadvantage when compared to a core formed entirely from TiO₂. In anexample, the shell that is disposed over the core is comprised of one ormore layers of a conventional pigment material, i.e., a material havinga high index of refraction such as TiO₂. Thus, an advantage of suchcomposite material is that it has a desired high index of refraction(approaching that of conventional solid TiO₂), provided by the TiO₂shell, and provides such desired property at a reduced cost (whencompared to conventional solid TiO₂), by using a different core materialthat is relatively less costly than TiO₂. Additionally, aluminumphosphate composite materials as disclosed herein can be engineered toprovide one or more additional performance properties. For example,aluminum phosphate composite materials can be engineered to additionallyprovide a desired degree of corrosion resistance and/or to provide adesired degree of antimicrobial protection depending on the particularend-use coating or formulation application. This is in addition toserving as a conventional pigment replacement and/or pigment extender.

An example core material useful for forming composite materials asdisclosed herein is solid aluminum phosphate (AlP), which may be used inamorphous form, crystalline form, or a combination thereof. The AlP canbe formed having a desired particle size during the chemical synthesisprocess, or can be sized after a chemical synthesis process byconventional sizing techniques. In an example, the AlP particle has anaverage particle size of less than about 30 microns, in the range offrom about 3 to 20 microns, and preferably in the range of from about 5to 10 microns. Ultimately, the end-use application will influence theparticular size of the AlP particle and/or AlP particle distributionthat is used for the core. Generally, the majority of coatings aremedium and low gloss, and an average pigment particle size much overabout 10 microns may end-use applications to those where a low degree ofgloss is desired.

The term “particle” as used herein with respect to the AlP core isunderstood to mean an aggregate of a number of smaller AlP primarygrains or powder that have joined or aggregated together during theprocess of synthesizing the AlP. The exact number of smaller AlP primarygrains or powder that combine to form each ALP particle or aggregateuseful for forming the core can and will vary. Accordingly, it is to beunderstood that the core component of the composite material comprisesan AlP aggregate formed from a plurality of primary AlP grains or powderas described above.

The AlP core material is preferably substantially irregular in shape,but can have a shape that is spherical, flat, or needle like if calledfor by a particular end-use application. For example, it may bedesirable in certain applications to have composite material that has ahigh aspect ratio, or that is flat like a flake or the like.Accordingly, it is to be understood that the core material as disclosedherein can be engineered having a variety of different shapes as calledfor by a particular end-use application.

An example shell material useful for forming composite materials asdisclosed herein is one having an index of refraction that is greaterthan that of the core material (e.g., AlP has an index of refraction ofless than about 1.55), so as to make the resulting composite materialsuitable to serve as a replacement and/or extender of conventionalpigment. In an example, it is desired that the shell material have anindex of refraction that is greater than about 1.55, greater than about1.7, and preferably greater than about 2. In a preferred embodiment, theshell material is formed from TiO₂, which has an index of refraction ofabout 2.6. In a particularly preferred embodiment, the TiO₂ is one thathas been surface treated with alumina, and/or silica or a combination ofalumina and silica, or the like, e.g., rutile grade TiO₂, to enhanceboth light stability and pigment dispersibility. Alternatively, the TiO₂can be treated with any other material that may be reactive with pendantPOH groups of the AlP core to thereby adhere to and form a shell withthe AlP core.

TiO₂ useful for forming the shell of the composite material has anaverage grain or powder size that is less than about 10 microns, in therange of from about 0.1 to 5 microns, and preferably in the range offrom about 0.3 to 1 microns. In certain end-use applications a desiredTiO₂ particle size for opacity is about 0.3 microns. Thus, using a TiO₂particle size greater or less than 0.3 microns may not provide a levelor degree of opacity for certain end-use applications.

In an example embodiment, the TiO₂ is placed into contact with the AlPparticles or cores, and is attached to the surface of the AlP cores toby reaction between the core and the TiO₂ as better described below.Thus, in an example embodiment, AlP composite materials as disclosedherein comprise a reaction product interposed between the core and theshell that operates to bond the shell to the core. In an example, theTiO₂ shell can have an average thickness of at least 0.0001 microns, inthe range of from about 0.001 to 2 microns, and preferably in the rangeof from about 0.01 to 1 microns. Generally, the TiO₂ shell or layer isformed having a thickness sufficient to provide a desired degree ofbrightness or index of refraction for a particular end-use applicationwithout using excess TiO₂ material that would unnecessarily add to theraw material cost of the composite material. The TiO2 shell may have athickness that may or may not be uniform along the core. Thus, the shellthicknesses provided above are representative of an average taken alongdifferent portions of the core surface.

The TiO₂ shell can cover the entire outside surface of the corematerial, i.e., it can encapsulate the core, or can cover a partialregion or portion of the core outside surface. The extent of shellcoverage over the core surface depends on such factors as whether thecomposite material is being used as the primary formulation pigment,whether it is being used as an extender pigment in conjunction withanother pigment material, the desired degree of brightness desired forthe particular end-use application, the particular material used to formthe core, and particular material selected to use the shell, and thelike.

In an example, where the core is AlP and the shell is TiO₂,it is desiredthat the TiO₂ shell cover a portion of the core surface sufficient toprovide a degree of brightness or index of refraction sufficient to actas a primary or extender pigment. In such example, the TiO₂ shell coversat least about 20 percent of the core outside surface, in the range offrom about 30 to 100 percent, and preferably in the range of from about50 to 75 percent of the core outside surface. The exact degree of TiO₂shell coverage as noted above can and will vary depending on theparticular end-use application. Additionally, the amount of shellcoverage can vary depending on the particular shell material that isused, e.g., if the shell material is a material other than TiO₂. Forexample, for shell materials having an index of refraction that is lessthan TiO₂, a higher degree of coverage may be useful to obtain a degreeof brightness for the composite material than that achieved using TiO₂.

FIG. 1 is a photomicrograph of an aluminum phosphate composite materialas disclosed herein. Specifically, this figure illustrates across-section of an aluminum phosphate composite 10 comprising a AlPcore 12 in the form of an AlP particle or aggregate 14, and a TiO₂ shell16 disposed over an outside surface 16 of the AlP core 12. Asillustrated, the shell 16 may comprise a single TiO₂ particle or maycomprise a number of TiO₂ particles that are combined with one another.In the example, the shell has a thickness that varies along the coresurface. As illustrated, the AlP core comprises an aggregate of a numberof smaller primary AlP particles 18 that are bonded with one another.The particle or aggregate 14 may include a plurality of openinterstitial regions 20 that exist between the primary AlP particles.These interstitial regions can be empty or may include one or moredesired materials disposed therein. In the example illustrated in FIG.1, some of the interstitial regions are shown to include TiO₂ disposedtherein.

The TiO₂ can be introduced into the AlP particle during the process ofcombining the AlP cores with the TiO₂ material. Alternatively, the TiO₂may be introduced into the interstitial regions when the AlP compositematerial is sized, which operation may cause some of the cores to beopened up and thereby exposing the interstitial regions to any free TiO₂that may be present. Besides or in addition to TiO₂, the AlP core can betreated to include one or more other materials disposed within theinterstitial regions as called for or desired by the particular end-useapplication, wherein such other material can operate to introduce aparticular performance property or characteristic.

For end-use applications calling for a certain degree of corrosionresistance, it may be desired to leave a portion of the underlying AlPcore exposed. AlP as disclosed herein is a corrosion inhibitingmaterial, capable of releasing passivating phosphate anion when placedinto contact with moisture that operates to inhibit corrosion ofmetallic substrates. AlPs useful in this regard include those made inaccordance with the references disclosed below and incorporated herein.Thus, a feature of AlPs as used herein as the core is that they canprovide a controlled delivery of phosphate anions, of about 50 to 1,500ppm, when contacted with moisture.

In addition to the corrosion inhibition mechanism of controlledphosphate anion release, such AlPs used as the core are capable ofabsorbing up to about 25 percent by weight moisture that they come intocontact with. Thus, when present for example in the form of a curedfilm, such AlP core materials function as a sort of sponge to absorb andthus contain moisture entering the film, and thereby operate to preventsuch moisture from traveling further through the film to an underlyingmetallic substrate where it can cause the substrate to corrode. This isin addition to the AlP forming a corrosion inhibiting passivating filmon the metallic substrate by reaction of the released phosphate anionand the metallic substrate. Further, in addition to phosphate anionrelease, AlPs as disclosed herein can be engineered to include one ormore other materials useful for providing anticorrosion resistance,examples of which include and are not limited to zinc, calcium,strontium, chromate, borate, barium, magnesium, molybdenum, andcombinations thereof.

The AlP core material can be formed according to a variety of differentprocesses and methods, including those disclosed in US PatentApplication Publication Nos. 2006/0045831, 2009/0217481, 2010/0203318,2012/0091397, 2012/0094128, 2012/0094130, and U.S. Pat. Nos. 7,763,359and 7,951,309, each of which is incorporated herein by reference in itsentirety. Additionally, AlP core materials formed according to thereferences disclosed above can have the same properties of those AlPdisclosed in the same references, as again incorporated herein byreference.

AlP core materials are generally formed by combining an aluminum sourcewith a phosphate source, in desired proportions, under desired pHconditions, and under desired conditions of temperature, to result inthe formation comprising solid AlP particles. As disclosed in thereferences disclosed and incorporated herein above, the AlP particlescan be formed by precipitation methods, binary condensation, and sol gelmethods.

Generally, the precipitation method of making AlP involves combining asuitable aluminum source such as aluminum sulfate or sodium aluminatewith a suitable phosphate source such as phosphoric acid using desiredaluminum and phosphate ratios, and using desired pH and/or temperatureconditions to form AlP. The binary condensation method of making AlPinvolves combining a suitable aluminum source such as aluminum hydroxidewith a suitable phosphate source such as phosphoric acid using desiredaluminum and phosphate ratios, adding acid to base or base to acid,wherein acidic aluminum phosphate may be formed as an intermediate, andusing desired pH and/or temperature conditions to form AlP. The sol gelmethod of making AlP involves combining an aluminum salt such asaluminum nitrate with phosphoric acid and adding to the mixturesufficient ammonium hydroxide sufficient to form an aggregate ofcolloidal AlP forming a gel having a three-dimensional structure oflinked amorphous aluminum phosphate particles.

Still further, AlP materials useful as the core of the compositematerial as disclosed herein can be engineered to incorporate one ormore ingredients other than phosphate therein for controlled release toprovide certain desired chemical composition or coating performance. Forexample, AlP materials useful as the core can be synthesized toincorporate one or more active material therein, such as Ag, Cu, Zn, Ca,Ni, Sr, and combinations thereof that may be useful to provide suchperformance features as antimicrobial protection, to provideconductivity and/or antifouling resistance or the like.

AlP materials as used herein may also comprise organic materials(volatile or nonvolatile, fugitive or nonfugitive) for a variety ofreasons. For example, the inclusion of volatile materials may beincorporated to control pore volume, pore size, structure etc., (thesematerials could be volatilized with heat or vacuum as part of themanufacturing process). Fugitive active organic materials may be used toenhance antimicrobial resistance, enhance conductivity or antifoulingproperties, act as an antioxidant, and/or provide light stabilization orenhanced UV light stability for example. Nonfugitive organic moietiesmay be employed to provide functionality for additional modificationwith other reactive ingredients.

In an example, where antimicrobial protection is desired, the AlPmaterial can be formed by one or more of the same methods describedabove, in the references incorporated herein, by either combining thedesired active material with the AlP after the AlP has been formed, orby combining the desired active material at the time of synthesizing theAlP, to thereby form an AlP complex comprising the active materialincorporated into the AlP material. In an example, where the activematerial is Ag, the resulting AlP material or complex that is formed hasa controlled Ag release when in a cured film of about 5 to 1,000 ppm,which is sufficient to provide a desired level or antimicrobialprotection on the surface of the film.

For end-use applications calling for one or more of such additionalperformance features, it is desired that some portion of the underlyingAlP core remain exposed and not covered by the shell to thereby enablethe AlP core to function in the manner disclosed above to providedesired release of one or more of its constituents, and/or to providefor moisture absorption. Thus, in such applications wherein the AlP coreis engineered to provide multiple functions (as a core for the shell andas a carrier for constituent release) in the formulation, the degree ofAlP core coverage by the shell represents a compromise between theamount useful to provide a desired level of pigment performance as areplacement or extender and the amount useful to provide a desiredrelease of an AlP constituent content. It is, therefore, to beunderstood that such shell coverage amounts can vary depending on suchfactors as the particular end-use application, the type of activeingredient contained in the AlP core, the type of material used to formthe shell, and the like.

Composite materials and methods of making the same as disclosed hereinmay be better understood with reference to the following particularexample.

Example

Formation of Composite Material

An example composite material is prepared by combining an aluminumsource with a phosphate source in a water-borne system (to form a slurrycomprising AlP particles with pendent POH groups) and adding TiO₂ (sothe POH groups can be reacted with alumina surface treatment of theTiO₂) to the slurry to form a shell over the AlP particles. In anexample, the aluminum source is aluminum trihydroxide (ATH) and thephosphate source is orthophosphoric acid.

Dispersions of ATH and TiO₂

ATH was dispersed in deionized water in a container comprising a highspeed dispenser with a cowles blade. In an example, an ATH particle sizeof less than about 5 microns was desired. The high speed dispenser wasused to achieve a 7.5+Hegman gauge value, which occurred in about 90 to120 minutes depending on the solid content and total batch size. Theaverage solid content of the ATH dispersion as determined according toASTM D-2369 was from about 25 to 30 percent. A dispersion of TiO₂ wasformed by combining TiO₂ with deionized water and using a high speeddispenser with cowles blade until a 7.5+Hegman value was achieved, whichwas within about 90 to 120 minutes. The solid content of the TiO2dispersion as determined according to ASTM D-2369 was from about 55 to65 percent.

Synthesis of AlP

On solid base, one mole of the ATH solution prepared above was addedinto a reaction kettle along with an amount of deionized water. Thereaction kettle included a mechanical stirrer, a heating mantle, atemperature controller, a thermocouple, a condenser, and an additionfunnel containing one mole orthophosphoric acid on solid base (ATH toacid mole ratio set at approximately 1:1). The ATH and water solutionwas initially stirred at about 700 to 1,000 RPM, or in a way thatsplashing of solution did not occur within the reaction kettle. Aninitial reaction temperature was set at approximately 42° C., and atthis temperature addition of the orthophosphoric acid was started. Theaddition time for the acid was between about 19 to 21 minutes. After theacid was completely added the stirring speed was increased to a maximumpoint and the reaction temperature was increased to approximately 92° C.At this condition, reaction was continued for a further 3 hours formingAlP particles. The pH was monitored every hour. Normally, the pHstabilizes within about 3 hours. In general, the pH achieved within thistime (initial/stabilized pH) was about 3 to 3.8. The solids content ofAlP particles in the batch at this stage was approximately 20.26percent. The AlP particles in the batch comprised pendent POH groups.

Synthesis of Core-Shell Structure

Once the initial pH was achieved, an amount of the TiO₂ solutionprepared above was added to the reaction kettle, and stirring wascontinued for a further 90 minutes. The pH stabilized within this 90minute time, and was in the range of about 3.5 to 4.6. During this time,the pendent POH groups from the AlP particles reacted with the aluminasurface treatment on the TiO₂ causing the TiO₂ to be strongly attachedto the outer surface of the AlP particles, thereby forming a TiO₂ shellaround each AlP particle or core. At this stage the solids content ofthe batch was approximately 22.196 percent.

Reacting with Imidazole

An amount of imidazole was added to the reaction kettle. The amount ofthe imidazole used depended on the total solids combined above, i.e.,the ATH, orthophosphoric acid, and TiO₂. Depending on the pH achievedafter the TiO₂ solution was added to the AlP, the amount of imidazoleused in the system can vary between about 0.2325 percent to 2 percent toachieve a 5+final product pH. The imidazole is used to react with anyresidual POH groups to increase pH, and to improve wet adhesion to easedispersion of the resulting AlP composite material into the coatingformulation.

Filtration, Washing and Drying.

The final product was filtered using a Buckner funnel, and the filteredproduct was washed with deionized water. The deionized water amount wasapproximately 3.6 times the weight of the total solids of the batch. Thewashed product was dried at 110° C. under 26 in., Hg vacuum for a periodof approximately 24 hours. The final product was stored in a metalcontainer and consisted of the AlP composite material as disclosedherein, and had a d50 particle diameter of approximately 10 microns.

AlP composite materials as disclosed herein are specifically engineeredto provide a high index of refraction that is greater than that of thecore and relatively closer to that of the shell material, e.g., TiO₂,for the purpose of entirely or partially replacing the amount ofconventional pigment material used in chemical or coating formulation,and provide such features at a cost that is less than conventional solidTiO₂. Accordingly, the use of AlP composite materials as disclosedherein operate to provide desired level of brightness at a reducedprice, which price reduction depends on the amount of the AlP compositeused to replace conventional solid TiO₂.

In certain end-use applications, AlP composite materials as discussedherein can be used to replace up to about 100 percent of conventionalpigment material. In example embodiments, AlP composite materials asdisclosed herein can be used in conjunction with conventional pigmentsto offset the amount, and thereby the cost, of such other conventionalpigment that is used, and can comprise at least about 5 percent byweight of the total pigment used in a formulation, in the range of fromabout 10 to 80 percent by weight of the total pigment used, and in therange of from about 20 to 60 percent by weight of the total pigment usedin a chemical or coating formulation.

For example a 50/50 blend of conventional solid TiO₂ with the AlPcomposite material as disclosed herein that comprises 15 percent TiO₂present as the shell component of the composite provides a coatingcomposition having a contrast ratio, whiteness and opacity that iscomparable to that of a coating composition containing 100 percentconventional solid TiO₂. This example 50/50 blend provides a 35 percentreduction in the amount of total TiO₂, thereby providing an associatedsavings in raw material price.

AlP composite materials as disclosed herein can be used in conjunctionwith both solvent and water-based coating systems, e.g., comprisingsolvent and/or water-based binding polymers, to provide a desired levelof conventional pigment reduction. Examples of such binging polymersinclude polyurethanes, polyesters, solvent-based epoxies, solventlessepoxies, water-borne epoxies, epoxy copolymers, acrylics, acryliccopolymers, silicones, silicone copolymers, polysiloxanes, polysiloxanecopolymers, alkyds and combinations thereof.

Additionally, AlP composites materials as disclosed herein can be usedfor purposes other than as a pigment, e.g., they can be used asflatteners in coating compositions, this in addition to the additionaluses disclosed above, e.g., to provide anticorrosion and/orantimicrobial resistance. Further, the pendent reactive POH groups ofthe AlP core can be used to attach other elements, ingredients,compounds, inorganic or organic moieties (in addition to or in place ofthe pigment material) that can provide certain other desired propertiesto the composite.

AlP composite materials as disclosed above provide a novel pigmentreplacement and/or pigment extender that may provide additionalproperties. While such AlP composite materials have been the inventionhas been described with respect to a limited number of embodiments, thespecific features of one embodiment should not be attributed to otherembodiments of AlP composite materials as disclosed herein. No singleembodiment is representative of all aspects of AlP composite materialsas disclosed herein. Variations and modifications from the AlP compositematerials described herein exist. The method of making AlP compositematerials is described as comprising a number of acts or steps byreference or otherwise. These steps or acts may be practiced in anysequence or order unless otherwise indicated. Finally, any numberdisclosed herein should be construed to mean approximate, regardless ofwhether the word “about” or “approximately” is used in describing thenumber. The appended claims intend to cover all those modifications andvariations as falling within the scope of AlP composite materials asdisclosed herein.

1-37. (canceled)
 38. A method for making an aluminum phosphate compositematerial comprising the steps of: forming a dispersion of aluminumphosphate particles; and combining aluminum phosphate particles with apigment material having an index of refraction greater than the aluminumphosphate particles so that the pigment material at least partiallycovers the aluminum phosphate particles to form the aluminum phosphatecomposite material.
 39. The method as recited in claim 38 wherein duringthe step of combining, the pigment material is TiO₂.
 40. The method asrecited in claim 38 further comprising after the step of combining,adding imidazole to the aluminum phosphate composite material.
 41. Themethod as recited in claim 38 comprising reacting the aluminum phosphateparticles with the pigment material to form a reaction product therebetween.
 42. The method as recited in claim 41 wherein the pigmentmaterial is TiO₂.
 43. The method as recited in claim 41 wherein duringthe step of reacting, POH groups from the aluminum phosphate particlesreact with a constituent of the pigment material.
 44. The method asrecited in claim 38 wherein during the step of forming, aluminumtrihydroxide is combined with phosphoric acid.